Ask the Dietitian: Do I Have To Worry About Vitamin B12?

Q: I’ve heard that most cases of vitamin B12 deficiency have nothing to do with diet but are due to problems with vitamin B12 absorption. And therefore, meat eaters are just as likely to have B12 deficiency as vegans. Is this true?

Ginny Messina, R.D.:

It’s true that problems with absorption are the most common reasons for vitamin B12 deficiency among non-vegans. Some people fail to produce adequate amounts of intrinsic factor, a protein that is essential for absorption of vitamin B12. Lack of intrinsic factor is commonly called pernicious anemia (although that term has fallen out of favor). It’s often an autoimmune condition in which the body’s immune system attacks the cells making intrinsic factor. It’s commonly treated with B12 injections, although very high daily doses of supplemental vitamin B12 can also be effective.

Pernicious anemia can occur in anyone, but is most common in older people. Many older people also experience poor vitamin B12 absorption because of declining levels of stomach acid. This is a completely different problem, though. People with this condition may have problems absorbing vitamin B12 from food, but can usually absorb it well from supplements.

Since meat-eaters typically have adequate vitamin B12 in their diet, these absorption issues are the most common reasons for vitamin B12 deficiency. For vegans who don’t take supplements (or eat fortified foods), though, a lack of vitamin B12 in their diet is the most likely reason for deficiency.

The bottom line is that anyone, no matter what they eat, can develop problems with vitamin B12 absorptions. But everyone needs adequate vitamin B12 in their diet. For vegans, the only choices are supplements or foods fortified with vitamin B12.

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